1. Field of the Invention
The present invention relates to barrier units and to articles made therefrom. More particularly, this invention relates to various constraining bands of high strength and low weight for containing articles such as logs or containers. Most particularly, this invention relates to blast resistant container assemblies for receiving explosive articles and preventing or minimizing damage in the event of an explosion. These container assemblies have utility as containment and transport devices for hazardous materials such as gunpowder and explosives, e.g., bombs and grenades, particularly in aircraft where weight is an important consideration, and more particularly in the cargo holds and passenger cabins of the aircraft. They are also particularly useful to bomb squad personnel in combating terrorist and other threats.
2. The Prior Art
In response to the 1988 terrorist bombing of a Pan American flight over Lockerbie, Scotland, experts in explosives and aircraft-survivability techniques have studied ways to make commercial airliners more resistant to terrorist bombs. One result of these studies has been the development and deployment of new generations of explosive detection devices. As a practical matter, however, there remains a threshold bomb size above which detection is relatively easy but below which an increasing fraction of bombs will go undetected. An undetected bomb likely would find its way into luggage either carried on board (in cabin) by a passenger or stored in an aircraft cargo container. Cargo containers, shaped as cubic boxes with a truncated edge, have typically been made of aluminum, which is lightweight but not explosion-proof. As a consequence, there has been tremendous focus in recent years on redesigning containers to be both blast resistant to bombs that are below this threshold size and lightweight.
A good overview on redesigned aircraft cargo containers is found in Ashley, S., SAFETY IN THE SKY: Designing Bomb-Resistant Baggage Containers, Mechanical Engineering, v 114, n 6, June 1992, pp 81-86, hereby incorporated by reference. One type of container disclosed by this article is designed to suppress shock waves and contain exploding fragments while safely bleeding off or venting high pressure gases, while another type is designed to guide explosive products overboard by channeling blast forces out of and away from the airplane hull. Several of the new designs utilize composite materials that are both strong and lightweight. In one such design, a hardened luggage container is wrapped in a blanket woven from low density materials such as SPECTRA® fibers, commercially available from AlliedSignal Inc., and lined with a rigid polyurethane foam and perforated aluminum alloy sheet. A sandwich of this material covers four sides of the container in a seamless shell. In this regard, see also U.S. Pat. No. 5,267,665, hereby incorporated by reference.
Access to a container's interior is necessary for loading and unloading and is typically provided by doors. Doors provide a significant weak point for the container during an explosion since a blast from within the container forces a typical door outward. If the door is connected through a hinge and metal pin arrangement, the pins can become dangerous projectiles. If the door slides in grooves or channels, the grooves or channels may bend or distort to cause failure of the container. It would thus be desirable to have a container design that eliminates the aforesaid problems with doors for access to the container's interior.
U.S. Pat. No. 5,312,182 discloses hardened cargo containers wherein the door engages by sliding in grooves/tracks with an interlock that ostensibly responds to such an explosive blast by gripping tighter to resist rupture of the device. The parent of this case, pending application Ser. No. 08/533,589, filed Sep. 25, 1995, addresses the door closure problem by utilizing at least three nested, mutually reinforcing, perpendicular bands of, preferably, a blast resistant material. Access to the interior of the container is provided by at least partially removing the two outer bands; this has not been found to be a user-friendly solution due to space contraints of the container on an aircraft.
Other blast resistant and/or blast directing containers are described in European Patent Publication 0 572 965 A1 and in U.S. Pat. Nos. 5,376,426; 5,249,534; and 5,170,690. All of these publications are hereby incorporated by reference. Other relevant art is represented by U.S. Pat. Nos. 5,333,532; 5,238,305; 4,809,402; 4,231,135, all hereby incorporated by reference.
The present invention, which was developed to overcome the deficiencies of the prior art, provides barrier units, constraining bands, and blast resistant container assemblies made therefrom.